Friday, February 20, 2015

When the sun becomes a red giant, the simple calculation would put
its equator out past Mars. All of the inner planets would be consumed.

However, as the Sun reaches this late stage in its stellar evolution,
it loses a tremendous amount of mass through powerful stellar winds. As
it grows, it loses mass, causing the planets to spiral outwards. So the
question is, will the expanding Sun overtake the planets spiraling
outwards, or will Earth (and maybe even Venus) escape its grasp.

The third largest extinction in Earth's
history, the Ordovician-Silurian mass extinction had two peak dying
times separated by hundreds of thousands of years. During the
Ordovician, most life was in the sea, so it was sea creatures such as
trilobites, brachiopods and graptolites that were drastically reduced in
number. In all, some 85% of sea life was wiped out. An ice age has been
blamed for the extinctions - a huge ice sheet in the southern
hemisphere caused climate change and a fall in sea level, and messed
with the chemistry of the oceans.

A diorama portraying the seas of the Ordovician Period (from the Exhibit Museum, University of Michigan)

Monday, February 16, 2015

Galaxies extend as far as we can detect... with no sign of diminishing.There
is no evidence that the universe has an edge. The part of the
universe we can observe from Earth is filled more or less uniformly
with galaxies extending in every direction as far as we can see
- more than 10 billion light-years, or about 6 billion trillion
miles. We know that the galaxies must extend much further than
we can see, but we do not know whether the universe is infinite
or not. When astronomers sometimes refer (carelessly!) to galaxies "near
the edge of the universe," they are referring
only to the edge of the OBSERVABLE universe - i.e., the part we can see.

Saturday, February 14, 2015

A Seismic Adventure

There's a giant crystal buried deep within the Earth, at the very
center, more than 3,000 miles down. It may sound like the latest fantasy
adventure game or a new Indiana Jones movie, but it happens to be what
scientists discovered in 1995 with a sophisticated computer model of
Earth's inner core. This remarkable finding, which offers plausible
solutions to some perplexing geophysical puzzles, is transforming what
Earth scientists think about the most remote part of our planet.

Friday, February 13, 2015

About 4 to 3.8 billion years ago a period of intense comet and asteroid bombardment is thought to have peppered all the planets including the Earth. Many of the numerous craters found on the Moon and other bodies in the Solar System record this event.
One theory holds that a gravitational surge caused by the orbital interaction of Jupiter and Saturn sent Neptune careening into the ring of comets
in the outer Solar System. The disrupted comets were sent in all
directions and collided with the planets. These water-rich objects may
have provided much of the water in the Earth's oceans.
The record of this event is all but lost on the Earth because our planet's tectonic plate system and active erosion ensure that the surface is constantly renewed.

Monday, February 9, 2015

Saturn is the sixth planet from the sun and the second largest planet
in the solar system. Saturn was the Roman name for Cronus, the lord of
the Titans in Greek mythology. Saturn is the root of the English word
"Saturday."

Saturn is the farthest planet from Earth visible to the naked human
eye, but it is through a telescope that the planet's most outstanding
features can be seen: Saturn's rings. Although the other gas giants in
the solar system — Jupiter, Uranus and Neptune — also have rings, those
of Saturn are without a doubt the most extraordinary.

Sunday, February 8, 2015

The smallest of the planets in the Solar System, Mercury is an interesting place. Incredibly dense due to its proportionately large core Mercury is thought to have been once a much larger planet.

Mercury is the smallest planet —
it is only slightly larger than Earth's moon. Since it has no
significant atmosphere to stop impacts, the planet is pockmarked with
craters. About 4 billion years ago, an asteroid roughly 60 miles (100
kilometers) wide struck Mercury with an impact equal to 1 trillion
1-megaton bombs, creating a vast impact crater roughly 960 miles (1,550
km) wide. Known as the Caloris Basin, this crater could hold the entire
state of Texas. Another large impact may have helped create the
planet’s odd spin.